Racing the Beam: How Atari 2600's Crazy Hardware Changed Game Design
By Chris Kohler March 13, 2009 | 2:26:00 PM Categories: Retrogames
The Atari Video Computer System was, in fascinating ways, unlike any other videogame console.
As the first wildly successful home game machine, the VCS, also known as the Atari 2600, was in millions of homes for well over a decade after its 1977 release. Even after Atari fell out of favor and Nintendo took over the 8-bit game business, the company continued to produce VCS games and hardware until 1992. (Let's see if Nintendo is still manufacturing Wii consoles in 2021.)
The VCS' unrivaled longevity is all the more astounding when one considers that the hardware itself was nearly obsolete even when it was first released. The VCS' unique hardware limitations forced game designers to jump through all sorts of hoops to squeeze more complex game designs out of the VCS. In a new book from MIT Press titled Racing the Beam: The Atari Video Computer System, media studies professors Nick Montfort and Ian Bogost present an engaging, fascinating look at the VCS platform and how it changed the nature of game design.
"The minimal but exploitable design of the VCS showed how long unexpected tricks and techniques could continue to be developed on a platform, over more than a decade. It showed that there's more to a console than is understood when it's first released," says Bogost.
In the book, Montfort and Bogost explain that the primary difference between the VCS and most every other game console is the machine's lack of a "frame buffer." This is the section of a system's RAM that saves the image data for each successive screen that the game displays. The programmer writes each image to RAM, and they are flashed up onto the television screen in succession.
The Atari VCS had a miniscule 128 bytes (that's bytes) of RAM, not nearly enough for a frame buffer. So programmers had to generate graphics literally in real time, drawing on the screen as the television screen's electron gun was passing over the tube.
As illustrated in this image from Racing the Beam, the electron gun's movement included three large spaces where it was not drawing on the screen: the vertical and horizontal "blanks" on the top and left, and the "overscan" on the bottom. These blind spots were crucial for Atari programmers, as these were the only times they could do anything that didn't involve drawing graphics on the screen, such as computing joystick inputs, player movements, scoring, etc.
If you've ever seen little black lines appear at the left edge of the screen while you're playing a VCS game, those are bits of the game's code where the program is taking too much time doing other calculations, and it can't draw on the screen, leaving it blank. The black bar on the left-hand side of the Pitfall! screen at top was Activision designers' solution — they cut out part of the gameplay field in exchange for more processing time.
As if all this weren't enough, the VCS could only display five interactive objects at any one time: two "player" sprites, two "missile" sprites, and one "ball." This was more than enough for replicating Pong and Tank, the popular arcade games of 1977. It was useless for anything even slightly more complicated, such as Space Invaders.
What saved the VCS, ironically, was the lack of a frame buffer. Yes, the system could only display two sprites at any given moment. But once the electron beam had drawn a sprite, the program could shift the position of said sprite horizontally and redraw it. But because the sprite had already been drawn on the screen, the original one would not disappear until the electron gun came back around to redraw the screen. By doing this, programmers could create rows and rows of sprites — perfect for Space Invaders' rows of aliens.
Eventually, use of these techniques allowed designers to create scenes on the VCS that were significantly more detailed than the hardware maker had ever imagined. Consider again the Pitfall screen at top. The tiny details in the tree's branches are drawn with sprites. When Pitfall Harry swings on a vine, that vine is drawn with the "ball" graphic intended for games of Pong.
Many of the most popular Atari VCS games were ports of popular arcade titles, a staple of the videogame industry that lasted long past the VCS' heyday. "The porting of arcade games to home systems was first really worked through on the VCS," says Bogost. "It was because of this VCS development that developers were able to figure out what to try to carry over and what to leave behind, and how to adapt the arcade experience for more limited consoles that would be played at home."
The most popular, and most notorious, arcade-to-Atari port was Pac-Man, released in 1981. The general consensus, then and now, is that the VCS version of Pac-Man totally sucks. The visual appeal of the arcade game is totally lost, and the gameplay doesn't fare much better in translation. It's considered to be one of the games that helped cause Atari's downfall.
But after you learn about the VCS hardware, its version of Pac-Man starts to seem more like a crowning achievement, not a massive stumble. If the 2600 could only display a handful of sprites on screen, how would a designer create a screen full of dots that could be individually eaten in any order? The answer turned out to be creating the dots using the same "playfield" graphics as the maze, so that every time you eat a dot, the game redraws the entire background.
Racing the Beam is an excellent book, chock full of fascinating tidbits that I've only scratched the surface of here. Other groundbreaking games examined in its chapters include Star Wars: The Empire Strikes Back and Adventure. Montfort and Bogost say it is the first in a series of "platform studies" that take an accessible, academically focused look at how gaming platforms affect how games are created.
http://blog.wired.com/games/2009/03/...-the-beam.html
Racing the Beam: How Atari 2600's Crazy Hardware Changed Game Design
